Clonidine associated with benzodiazepine before carotid endarterectomy decreases cerebrovascular CO2 reactivity.

Objective: Assess cerebrovascular CO2 reactivity changes using transcranial Doppler sonography (TCD) after oral premedication associating clonidine (2 mug.kg(-1)) and flunk trazepam (70 mug.kg(-1)) in patients scheduled for c arotid stenosis surgery. Study design: Prospective study, not randomized, the patient being his own "control". Patients and methods: Thirteen patients undergoing carotid endarterectomy u nder cervical plexus block were included. The monitoring included: automate d arterial pressure cuff, ECG, radial artery catheter, TCD with probe secur ed in temporal window. The study of the cerebrovascular CO2 reactivity was performed with TCD recording on the side of operation, on the day before, a nd on the day of carotid endarterectomy, 90 min after the premedication, im mediately before surgery. To change PaCO2, four ventilatory states were suc cessively performed : (1) normoventilation, (2) hyperventilation, (3) hypov entilation, (4) "breath-holding test". At each state, it was noted : HR, MA P, PaCO2, mean blood flow velocity in the middle cerebral artery (Vm-MCA), resistance index of Pourcelot (RI), cerebrovascular reactivity (slope Vm-MC A / PaCO2). The results (+/- SEM) were analyzed by Wilcoxon test or t test. Results: After premedication, cerebrovascular CO2 reactivity decreased (0.0 43 +/- 0.019 vs 0.034 +/- 0.013; p < 0.05) without modification of RI (0.57 8 +/- 0.291 vs 0.612 +/- 0.025; NS). No complication during carotid clampin g was reported. Conclusion: Inclusion of clonidine in premedication before carotid stenosis surgery must be questioned because a decrease of cerebrovascular CO2 react ivity could be deleterious in case of intraoperative stroke. (C) 2001 Editi ons scientifiques et medicales Elsevier SAS.